Internal combustion engines typically include various filtration systems, such as air filtration systems, fuel filtration systems, oil filtration systems, and the like. The filtration systems generally remove contaminants, such as dust and water, from fluids used by the internal combustion engine.
The air filtration system is part of an air intake system. The air filtration system filters intake air prior to routing the intake air to the engine. The air filtration systems remove dust, moisture, and other particulate from the intake air. The air filtration systems typically include a filter media (e.g., a paper-based filter media, a foam-based filter media, a cotton-based filter media, a pleated filter media, etc.) that processes the air. Some air filtration systems include a pre-cleaner positioned upstream of the filter media. A pre-cleaner removes at least a portion of the dust, moisture, and other particulate matter from the intake air prior to the intake air being processed by the filter media. Accordingly, the pre-cleaner extends the life of the filter media. The pre-cleaner may be an ejective pre-cleaner, a pre-filter pre-cleaner, a cyclonic pre-cleaner, or the like. The specific type of pre-cleaner may be selected based on the worst dust loading conditions that an internal combustion engine is expected to see during operation.
A pre-cleaner, however, also causes parasitic air pressure losses in the air intake system due to the increased restriction caused by the pre-cleaner. The parasitic losses are present even when the pre-cleaner is unnecessary (e.g., when the internal combustion engine is operating in a clean air environment). The parasitic losses may cause higher pumping loss, thereby reducing the fuel economy for the internal combustion engine (e.g., reduced miles per gallon in a vehicle application, fewer operating hours per tank in a generator or construction application, etc.). The reduced fuel economy increases operating costs (i.e., increases fuel costs).
Other filtration systems, such as fuel, oil, and hydraulic fluid filtration systems, filter liquids that are used by the internal combustion engine or used to drive equipment. Generally, these filtration systems draw fluid to be filtered from a tank (e.g., a fuel tank, an oil tank, a hydraulic fluid tank, etc.). Certain operating conditions can cause the fluid to have increased contamination levels. Specifically, contaminant particles may be re-entrained from the surfaces of piping, filter media, tank bottoms, and the like during certain transient conditions, such as fluid flow surges, vibrations, and the like. This is particularly problematic during tank fill up and engine or hydraulic system start up events. During tank fill ups, elevated contamination levels may be found in the new (but frequently not clean) liquid introduced into the tank. Contaminant levels are further increased by the resuspension of contaminant from tank bottoms and walls by the filling operation itself. When an engine or hydraulic system is started, the liquid flow rate to the downstream components, including the filtration system, goes from zero to operating flow rates in a matter of seconds or even less. As such, extremely high contamination levels are temporarily observed as the fluid accelerates from a generally stationary position to a moving stream. During these periods, wear induced damage to downstream components is especially high. Orders of magnitude increases in fuel contamination levels have been observed at engine start up and during rapid changes in flow rate. Such increases in the liquid born contamination reduce component life, reduce engine reliability, and reduce overall system robustness. These increases in contamination levels also have the potential to shorten the useful life of the filtration system. Additionally, the introduction of the multiple filter elements, much like the above-described pre-cleaners for air filtration systems, introduces greater restriction to the filtration systems thereby causing parasitic liquid pressure losses in the filtration systems.